Various electronic calipers are known that use electronic position encoders. These encoders are generally based on low-power inductive, capacitive, or magnetic position sensing technology. In general, an encoder may comprise a readhead and a scale. The readhead may generally comprise a readhead sensor and readhead electronics. The readhead outputs signals that vary as a function of the position of the readhead sensor relative to the scale, along a measuring axis. In an electronic caliper the scale is generally affixed to an elongated scale member that includes a first measuring jaw and the readhead is affixed to a slider which is movable along the scale member and which includes a second measuring jaw. Thus, measurements of the distance between the two measuring jaws may be determined based on the signals from the readhead.
Exemplary electronic calipers are disclosed in commonly assigned U.S. Pat. Nos. RE37,490, 5,574,381, and 5,973,494, each of which is hereby incorporated by reference in its entirety. A prior art electronic caliper that is capable of measuring force is disclosed in U.S. Patent Publication No. 2003/0047009. As described in the '009 publication, one deficiency in the use of prior calipers is the variation in force which can be applied by the measuring jaws and the differences in measurement which can occur as a result. This is particularly true when a soft object is being measured, where the measurement of the object may be altered by one measurer applying a high level of force on the jaws of the caliper and thereby partially indenting the soft object, while another measurer applies a low level of force such that the soft object is not indented. As a solution, the '009 publication discloses a caliper that is capable of measuring both the size and force applied to an object. However, while the caliper of the '009 publication does take force measurements, it does not determine and indicate an appropriate level of force that should be applied in order for accurate measurements to be obtained. Furthermore, it suggests that a size may be measured when a predetermined pressure is applied, and the pressure and corresponding size may be reported, but this is not a mode of operation that the typical caliper user would find ergonomically or perceptually conventional or convenient, and therefore it would not be intuitively understandable. For example, a user expects a caliper position display (which has a minimal size and cannot display large of amounts of information simultaneously) to track the caliper slider position, not suddenly freeze at a particular pressure. As a further example, the '009 publication indicates that friction may affect a force reading, but does not suggest an ergonomically or perceptually convenient way of addressing this issue. A need exists for a method for establishing and indicating an appropriate level of force to be utilized for the measurement of an object with a caliper in an ergonomically convenient, and intuitively understandable manner.